What's in sunscreen lotion?

Check out the ingredients list on that tube. It might persuade you to hit the shade.

Q: I’ve heard so much conflicting information about sunscreen lately — which kind to use, what ingredients are best, you name it. Could you help me sort it all out?

A: Choosing sunscreen used to be a no-brainer, right? You just stopped at the pharmacy, picked up whatever brand was on sale, and slathered it on before a day at the beach, confident that the sun’s rays wouldn’t harm you at all. What we didn’t know is that ingredients in sunscreen may be doing more harm to us than the rays it’s supposed to be protecting us from in the first place. Now choosing the right sunscreen seems to be a maze of choices and wrong turns. So what to do?

Let’s take a little sunscreen primer, shall we? Sunscreens on the market today fall into two major categories — chemical sunscreens and mineral sunscreens. Chemical sunscreens contain chemicals that get absorbed into the skin that then, in turn, absorb the sun’s rays. Mineral sunscreens usually have one of two main ingredients — zinc oxide or titanium dioxide (or sometimes a combination of both) and instead of absorbing the sun’s rays, they block them instead.

For a long time, chemical sunscreens seemed to be the more popular choice among Americans. Then studies came out that linked some of their chemical ingredients, namely oxybenzone, to hormone and endocrine disruption. So the answer is to use mineral sunscreens, right? Well, maybe. Turns out mineral sunscreens have their own potential risk factors called nanoparticles, highlighted by the environmental organization Friends of the Earth in 2006.

Another difference between these two types of sunscreen is the type of radiation that they block. Traditionally, chemical sunscreens are really great at blocking UVB rays, which contribute to cancer and also cause sunburn. Mineral sunscreens also block UVB rays and have the added benefit of helping to protect against UVA rays, which are known to contribute to early aging (wrinkles and the like) and can cause cancer. The SPF on the bottle only refers to the sunscreen’s UVB-protecting ability. The FDA is working on new guidelines that would require all sunscreens to have a UVA rating (one to four stars) next to the SPF rating. Proposed in 2007, the guidelines will go into effect this year, and will take a year or so for companies to implement. But the New York Times says don’t hold your breath.

So what’s a sun-loving gal to do? First of all, the International Agency for Research on Cancer suggests that sunscreen not be your first line of defense against the sun. Instead, you should seek shade when the sun is at its strongest (usually between the hours of 10 a.m. and 4 p.m.) and wear protective clothing. Interestingly, the group's research showed that sunscreen wearers actually stayed in the sun longer than they should because they thought they were protected from the sun’s harmful rays. (Sort of how I eat whatever I want when I’m pregnant because I assume I can’t gain any “bad” weight.)